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Ohms Law Low-current Calibration System for Ionization Chambers



Dean G. Jarrett, Shamith U. Payagala, Ryan P. Fitzgerald, Denis E. Bergeron, Jeffrey T. Cessna, Charles J. Waduwarage Perera, Neil M. Zimmerman


A system for the calibration of electrometers that measure currents from ionization chambers is described. The calibration system uses a 1 GΩ standard resistor in series with a stable voltage source to generate calibration currents from 1 pA to 20 nA, traceable to quantum voltage and resistance standards through an 8-1/2 digit digital voltmeter and the standard resistor. Expanded uncertainties (k = 2) of 100 x 10-6 or better for the calibration of the electrometer is needed for the ionization chamber measurements. The electrometer calibration was verified by current measurements following the decay of the short-lived radionuclide 18F in a re-entrant ionization chamber.
Proceedings Title
2020 Conference on Precision Electromagnetic Measurements(CPEM 2020)
Conference Dates
August 24-28, 2020
Conference Location
Denver, CO


electrometer, ionization chamber, quantum electrical standards, standard resistor, small current measurement


Jarrett, D. , Payagala, S. , Fitzgerald, R. , Bergeron, D. , Cessna, J. , Waduwarage, C. and Zimmerman, N. (2020), Ohms Law Low-current Calibration System for Ionization Chambers, 2020 Conference on Precision Electromagnetic Measurements(CPEM 2020), Denver, CO (Accessed September 24, 2023)
Created August 23, 2020, Updated September 1, 2020